1. Field of the Invention
The present invention relates generally to charged-particle beam lithography technologies and, more particularly, to a technique for converting pattern layout-defined design data to thereby create data for use in electron beam lithographic apparatus. This invention also relates to a pattern writing method and apparatus using the data conversion technique.
2. Related Art
Lithography that plays a role for advance in miniaturization of semiconductor devices is a very important process among semiconductor fabrication processes in light of its pattern generation feature unique thereto. In recent years, an increase in integration density of LSI chips results in a year by year decrease in circuit line width required for semiconductor devices. In order to form a desired circuit pattern on substrates of these semiconductor devices, a high-precision original image pattern (also known as a reticle or a mask) is required. Note here that electron ray (electron beam) pattern writing techniques have inherently excellent resolution properties and, for this reason, are used for the manufacture of such high-precision original patterns.
FIG. 10 is a conceptual diagram for explanation of an operation of one prior known electron beam pattern writing apparatus.
A variable-shaped electron beam (EB) pattern writing apparatus operates as follows. In a first aperture 410, a rectangular opening 411 is formed for shaping an electron beam 330. In a second aperture 420, a variable shaping opening 421 is formed for reshaping the electron beam 330 that has passed through the opening 411 into a desired rectangular shape. The electron beam 330 that was emitted from a charged particle source 430 and then passed through the opening 411 is deflected by a deflector. Then, it passes through part of the variable shaping opening 421 to be irradiated onto a workpiece 340, which is mounted on a stage. This stage is driven to continuously move in a prespecified one direction (e.g., X direction). More specifically, a rectangular beam shape that can penetrate both the opening 411 and the variable shaping opening 421 is drawn or written on the workpiece 340 in a pattern writing area thereof. The scheme for causing the beam to pass through both the opening 411 and the variable shaping opening 421 to form a desired shape is called the variable-shaped beam (VSB) technique.
When performing the electron beam pattern writing, what is done first is to design a semiconductor integrated circuit layout, thereby to generate layout data (design data) with a pattern layout defined therein. Then, in the prior art, the layout data is converted by an external device to thereby generate draw data capable of being input to the electron beam pattern writing apparatus. The draw data are transferred in unison to the writing apparatus all at once for input to the electron beam pattern writing apparatus so that pattern writing is performed based on the draw data in the pattern writing apparatus after having converted through a plurality of conversion processes into the format of such apparatus.
However, with growth in the quest for higher integration of LSIs, the electron beam pattern writing apparatus becomes huge in amount of data to be processed thereby. This poses a problem as to unwanted increases in time required to generate the draw data by the external device that becomes off-lined with the electron beam pattern writing apparatus and also in time taken to complete all-at-once transmission of the generated draw data to the electron beam pattern writing apparatus, resulting in an overall pattern writing time being appreciably increased. Simultaneously, this also causes unwanted increase in manufacturing costs of masks under pattern write processing.
Here, some teachings are disclosed as to the external device that becomes offlined, although not for the electron beam pattern writing apparatus per se. The external device (i.e., draw data creation device) is arranged to have a parallel combination of more than two arithmetic processing units for preparation of the draw data, which units are different from each other in stage number of series-connected processors. With such arrangement, it is asserted that even load significance-different design data is convertable into draw data by use of a pipeline configuration as suggested, for example, in JP-A-5-90141. Additionally, JP-A-2005-293333 discloses therein a technique for causing a host computer to transfer control contents to a device controller while letting the contents be divided into functions that are processable within a given length of time period, and for permitting the device controller to control a field device based on the functions in real time, although this technique is not specifically relevant to the electron beam lithography technology.
As has been described above, with a noticeable increase in data amount, prior art approaches are faced with a problem as to increases in the time needed for generation of draw data at the offlined external device and in the time taken for transmission in unison all at once of the generated draw data to the electron beam pattern writing apparatus, resulting in an unwanted increase in pattern writing time.